32GB setup 4 x 8Gb or 8 x 4GB

[Leonidsg]

This is probably a stupid question that I have been search for an answer to. Is there any difference in performance if I were to use 8 4GB sticks of memory vs 4 8GB sticks of memory in a Asus P9X79 Pro motherboard. It is quad channel. Thank you.

 

[thently]

no you will see no diffrence as long as you are using all 4 channels if you have 8 slots full the memory controller can still only addess 4 at a time so just does not matter if it is all the same speed ram.

Thent

 

[nna2]

ive heard the 8GB sticks are a bit slower, but i would go for that anyways, just so you could go up to 64GB if you choose to

^but as they said you wont see a difference

 

[Flyfisherman]

Hi,

Consider this; filling up all memory slots with ram sticks, will put more stress on the memory controller and the CPU.
More power will go through to operate all the memory sticks.

It's the number of memory sticks; Not the amount of memory that causes this.
So, for that reason, it could be a better choice to use 8GB memory sticks in four slots; although it could be somewhat slower timings on the bigger memory sticks.

Don't pay to much attention to that, since very little performance boost with faster timings and frequency will be noticeable in real life applications, compared to benchmark programs with their synthetic test patterns.

Another benefit with fewer memory sticks, is that perhaps the system could be more stable; less sensitive for slight differences between each memory stick.

And buy one matching memory kit 1,5V only.
Look into you motherboards QVL or almost all memory vendors has a memory configurator of some sort that is a good advice to use, since the Qualified Vendors List (QVL) from the manufacturer of the motherboard will not have all the memory's on the market on their QVL.

Asus P9X79 Pro Memory QVL
I find this in that list with tested memorys from ASUS:
Corsair CMT32GX3M4X1866C9 32GB Kit (4 x 8GB) 1333Mhz without XMP and 1866Mhz with XMP enabled. I recommend to run them without the XMP enabled, at least to begin with.
Take a look here if you later decides that you want higher speed: How to enable XMP

Or for example Corsairs memory finder and I looked up this for You, just scroll down the list:
Guaranteed-Compatible Memory for your Asus P9X79 PRO

Best Regards

[Edit] Depending on what O/S you have, which edition, it handles maximum amount of memory differently.
For example (32 bit system maximum 4GB about 3,5GB usable to the system):
Windows 7 64 bit Home Basic 8GB
Windows 7 64 bit Home Premium 16GB
Windows 7 64 bit Professional 192Gb
Windows 7 64 bit Ultimate 192GB

 

[jaquith]

Personally I have 8x4GB and in (2) kits primarily because I liked the DDR3L and the looks of the 'Gold' CMZ16GX3M4X1600C9G sets, filled DIMM slots, and it look 'pretty' with my 'Gold' Sabertooth X79 VRM heat sinks.

However, from a practical standpoint DDR3L are best for the CPU's durability, but neither looks or 8x_GB is a 'smart' choice. 8x4GB vs 4x8GB, clearly 4x8GB is best because you otherwise have a 200% higher risk of a failed DIMM slot or Stick.

Performance - There's little to no added benefit going above DDR3-1600 other than for something like a 'RAM Disk' and the increases in instability & error rate are also a factor so IMO stay with DDR3-1600. There is a factor of 4GB vs 8GB in that comparatively the 8GB/density often has a slightly higher CAS BUT R/W data from 8xDIMM slots vs 4xDIMM slots more than compensates and I listed a CAS 9 8GB/stick set below (best of both)

The Vengeance lines work but they work at Rated and very rarely can work beyond Rated without either significant compromising to sacrificing CAS to Frequency or way too high of Voltage --- compared to the extremely good and handpicked IC's of the Dominator or GT lines from Corsair.

The problems with either the Vengeance, Dominator or GT lines is that they are tall and will interfere with many conventional HSF assemblies e.g. Noctua NH-D14. However, on the SB-E/LGA 2011 I strongly advise either the Corsair H100 or H80 cooling or other exotic (block, radiator, pump, etc) cooling.

My suggestions:
32GB Kits:
(low profile) Mushkin Enhanced Blackline 32GB (4 x 8GB) DDR3 1600 (10-10-10-27 @ 1.50v) Model 994055 - http://www.newegg.com/Product/Product.aspx?Item=N82E16820226317
(low profile) Mushkin Enhanced Blackline 32GB (4 x 8GB) DDR3 1600 (9-9-9-24 @ 1.60v) Model 994050 - http://www.newegg.com/Product/Product.aspx?Item=N82E16820226315

(better IC's but tall for some HSF) CORSAIR DOMINATOR 32GB (4 x 8GB) DDR3 1600 (10-10-10-27 @ 1.50v) Model CMP32GX3M4X1600C10 - http://www.newegg.com/Product/Product.aspx?Item=N82E16820233229

Ideally 1.50v is best with a VCCSA (VICCO) of 1.1v-1.2v. CAS 9 with 8GB/stick is faster but requires more voltage to remain stable. Using any of those kits set use the e.g. ASUS AI Overclock Tuner -> XMP then save and everything will be set optimally and with any of the kits IF needed (8GB/stick or >DDR3-1600 is typical) set the VCCSA -> 1.10v~1.20v which is safe.

Any of those kits are good and safe long-term, VCCSA of 1.10v~1.20v and or DRAM Voltage of 1.50v is safest, but again 1.60v~1.65v is still fine especially on SB-E and IB CPUs. A higher than 1.50v DRAM Voltage is common for either Higher Frequencies (fast) and/or Lower CAS (fast), and CAS 9 with 8GB/stick is very fast plus as important as Frequency -- so the (2) kits of Mushkin 1.60v are very good.

 

[Leonidsg]

Personally I have 8x4GB and in (2) kits primarily because I liked the DDR3L and the looks of the 'Gold' CMZ16GX3M4X1600C9G sets, filled DIMM slots, and it look 'pretty' with my 'Gold' Sabertooth X79 VRM heat sinks.

However, from a practical standpoint DDR3L are best for the CPU's durability, but neither looks or 8x_GB is a 'smart' choice. 8x4GB vs 4x8GB, clearly 4x8GB is best because you otherwise have a 200% higher risk of a failed DIMM slot or Stick.

Performance - There's little to no added benefit going above DDR3-1600 other than for something like a 'RAM Disk' and the increases in instability & error rate are also a factor so IMO stay with DDR3-1600. There is a factor of 4GB vs 8GB in that comparatively the 8GB/density often has a slightly higher CAS BUT R/W data from 8xDIMM slots vs 4xDIMM slots more than compensates and I listed a CAS 9 8GB/stick set below (best of both)

The Vengeance lines work but they work at Rated and very rarely can work beyond Rated without either significant compromising to sacrificing CAS to Frequency or way too high of Voltage --- compared to the extremely good and handpicked IC's of the Dominator or GT lines from Corsair.

The problems with either the Vengeance, Dominator or GT lines is that they are tall and will interfere with many conventional HSF assemblies e.g. Noctua NH-D14. However, on the SB-E/LGA 2011 I strongly advise either the Corsair H100 or H80 cooling or other exotic (block, radiator, pump, etc) cooling.

My suggestions:
32GB Kits:
(low profile) Mushkin Enhanced Blackline 32GB (4 x 8GB) DDR3 1600 (10-10-10-27 @ 1.50v) Model 994055 - http://www.newegg.com/Product/Product.aspx?Item=N82E16820226317
(low profile) Mushkin Enhanced Blackline 32GB (4 x 8GB) DDR3 1600 (9-9-9-24 @ 1.60v) Model 994050 - http://www.newegg.com/Product/Product.aspx?Item=N82E16820226315

(better IC's but tall for some HSF) CORSAIR DOMINATOR 32GB (4 x 8GB) DDR3 1600 (10-10-10-27 @ 1.50v) Model CMP32GX3M4X1600C10 - http://www.newegg.com/Product/Product.aspx?Item=N82E16820233229

Ideally 1.50v is best with a VCCSA (VICCO) of 1.1v-1.2v. CAS 9 with 8GB/stick is faster but requires more voltage to remain stable. Using any of those kits set use the e.g. ASUS AI Overclock Tuner -> XMP then save and everything will be set optimally and with any of the kits IF needed (8GB/stick or >DDR3-1600 is typical) set the VCCSA -> 1.10v~1.20v which is safe.

Any of those kits are good and safe long-term, VCCSA of 1.10v~1.20v and or DRAM Voltage of 1.50v is safest, but again 1.60v~1.65v is still fine especially on SB-E and IB CPUs. A higher than 1.50v DRAM Voltage is common for either Higher Frequencies (fast) and/or Lower CAS (fast), and CAS 9 with 8GB/stick is very fast plus as important as Frequency -- so the (2) kits of Mushkin 1.60v are very good.

What do you think about the G Skill Ripjaws Z series. Thank you for your help.

 

[jaquith]

I see more issues with G.SKILL Ripjaws Z 8GB/density kits (stability & too many bad sticks), so until there's an IC revision or lesser issues only the 8GB/stick kits are off 'my' list. Several issues related to older versions of XMP, on LGA 2011 stay with version 1.3 <or> manually adjust the Frequency, primary CAS Timings, and VCCSA Voltage.

The older kit F3-12800CL10Q-32GBZL doesn't offer XMP 1.3, and I've seen the G.SKILL comments, but IMO they say and contradict themselves too often e.g. -> http://www.tomshardware.com/forum/313756-30-16gb-compatible-sabertooth#t2101367

Companies are bigger into marketing than Mushkin and for $0.50/kit sacrifice quality IC's as mentioned above.